Update README.md

Author: icebob

README.md

@@ -1,4 +1,6 @@
 # vue-websocket [![NPM version](https://img.shields.io/npm/v/vue-websocket.svg)](https://www.npmjs.com/package/vue-websocket)
+![VueJS v2.x compatible](https://img.shields.io/badge/vue%202.x-compatible-green.svg)
+
 Websocket (socket.io) plugin for VueJS. Support namespaces.